Percentage Calculator

Three quick calculators — results update as you type.

What is X% of Y?

% of = 16

X is what percent of Y?

is 20% of

Percentage increase / decrease

From to =

How to calculate percentages

A percentage expresses a number as a fraction of 100. The three calculators above cover the everyday cases:

Percent of a number: multiply the value by the percentage and divide by 100. 20% of 80 = 80 × 20 ÷ 100 = 16.
What percent: divide the part by the whole and multiply by 100. 16 ÷ 80 × 100 = 20%.
Percentage change: subtract the old value from the new, divide by the old value, multiply by 100. (100 − 80) ÷ 80 × 100 = 25%.

The three percentage formulas, in full

Almost every percentage question you meet in real life is one of three shapes. Knowing which shape you are looking at is most of the work; the arithmetic is trivial once you do.

Percent of a value → result = value × percent ÷ 100 What percent → percent = part ÷ whole × 100 Percentage change → change = (new − old) ÷ old × 100

Worked example: a discount

A jacket is $128 and the sign says 35% off.

Discount = 128 × 35 ÷ 100 = $44.80

You pay = 128 − 44.80 = $83.20

A shortcut for shopping: to take 35% off, multiply by 0.65 instead. One step, same answer — and it works for any discount, because paying 100 − d percent is the same as removing d percent.

Worked example: percentage change over time

Site visits went from 2,400 in June to 3,180 in July.

Change = (3,180 − 2,400) ÷ 2,400 × 100 = +32.5%

Note that the denominator is always the older value. Swap the two numbers and you get −24.5%, which is a different (and usually wrong) statement about the same pair of numbers.

Percentage points are not percentages

If a rate rises from 4% to 6%, that is a rise of two percentage points — but a 50% increase in the rate itself. Newspapers mix these up constantly. When you are describing a change in something that is already a percentage, say “percentage points” and the ambiguity disappears.

Why a 50% fall needs a 100% rise to recover

Percentage changes are asymmetric because the base moves. Drop $100 by 50% and you have $50; to get back to $100 you need to add $50 to a $50 base, which is a 100% gain. This is why consecutive percentage changes never simply add up: a 10% rise followed by a 10% fall leaves you at 99% of where you started.

Common percentage conversions

Percent	Fraction	Decimal	Multiply by
5%	1/20	0.05	÷ 20
10%	1/10	0.10	÷ 10
12.5%	1/8	0.125	÷ 8
20%	1/5	0.20	÷ 5
25%	1/4	0.25	÷ 4
33.3%	1/3	0.333	÷ 3
75%	3/4	0.75	× 3 ÷ 4

Rounding note: this calculator displays two decimal places but computes at full precision, so chained results stay accurate.

Percentage FAQ

How do I calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. For example, 20% of 80 is 80 × 20 ÷ 100 = 16. As a shortcut, move the decimal point one place left to get 10% and scale from there.

How do I calculate percentage change?

Subtract the old value from the new value, divide the result by the old value, then multiply by 100. Always divide by the older figure — that is the baseline the change is measured against.

What is the difference between percent and percentage points?

A move from 4% to 6% is a rise of two percentage points but a 50% increase in the rate. Use percentage points whenever the thing changing is itself a percentage.

How do I take a percentage off a price?

Subtract the discount from 100 and multiply by that. For 35% off, multiply the price by 0.65. For 20% off, multiply by 0.8.

Why does a 50% loss need a 100% gain to break even?

Because the base changes. A 50% loss on 100 leaves 50, and getting from 50 back to 100 means adding 50 to a base of 50 — a 100% gain.

Do percentage increases add up?

No. A 10% increase followed by a 10% decrease leaves you at 99% of the original, because the second percentage is applied to a larger base. Multiply the factors (1.10 × 0.90 = 0.99) instead of adding the percentages.

Recently used